It is known that synthetic polymers undergo a progressive change in their physical properties, such as loss of their mechanical strength and color changes, when they are exposed to sunlight or other sources of ultraviolet light.
It is hitherto well known that synthetic resins such as polyethylene, polypropylene, polyvinyl chloride, polyurethane, ABS resin, etc. deteriorate by the action of light, thereby showing a remarkable reduction in physical properties followed by phenomena such as softening, brittleness, discoloration and the like.
For the purpose of preventing such deterioration by light, the use of various photostabilizers is conventional. Such photostabilizers include for example 2-hydroxy-4-methoxybenzophenone. 2-hydroxy-4-n-octoxybenzophenone, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-dipentylphenyl)benzotriazole, ethyl 2-cyano-3,3-diphenylacrylate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate. [2,2'-thiobis(4-tert-octylphenolate)in-butylamine nickel(II), Ni salt of bis(3,5-di-tert-butyl-4-hydroxybenzylphosphoric acid)monoethyl ester, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate and the like. These photostabilizers, however, are not yet quite satisfactory in terms of light fastness, when used alone or in combination of sulfur-containing antioxidants(s).
U.S. Pat. No. 4,578,472 discloses a 2,2,6,6-tetramethylpiperidine derivative used for prevention of deterioration by light of synthetic resins produced by reacting a 4-amino-2,2,6,6-tetramethylpiperidine compound represented by the formula: ##STR2## wherein R.sub.1 represents a hydrogen atom or methyl group with a halogenated carboxylic acid or ester represented by the formula: ##STR3## wherein X represents a halogen atom, R.sub.3 represents an alkylene group having one to four carbon atoms, and R.sub.4 represents a hydrogen atom or lower alkyl group and then reacting the resulting reaction product with a 4-hydroxy-2,2,6,6-tetramethylpiperidine compound represented by the formula: ##STR4## wherein R.sub.2 represents a hydrogen atom or methyl group, in the presence of a basic catalyst.
In studying the destructive action of sunlight, it is clear that the rate of such degradation is greater, the greater the specific surface area of the polymer; therefore, manufactured articles with extensive surface development, such as fibers, tapes and films, more readily suffer photo-oxidative degradation. In order to delay the negative effect of ultraviolet radiation on synthetic polymers, it has been proposed to use various stabilizers which protect against light; in particular, for the light stabilization of articles of small thickness, such as fibers, tapes and films, it has been proposed to use products of polymeric nature, which contain polyalkylpiperidine radicals which, because of their relatively high molecular weight, are markedly resistant to volatilization and to extraction by water. Some of these products also show a marked effecacy as light stabilizers; in particular, U.S. Pat. No. 4,086,204 has claimed polytriazine compounds comprising, for example, compound of the formula ##STR5##
U.S. Pat. No. 4,102,248 has claimed, as stabilizers for polyolefins, polyamines comprising, for example, the compound of the formula: ##STR6## and U.S. Pat. No. 4,232,131 has claimed, likewise as stabilizers for polymers, polyamides comprising, for example, the compound of the formula:
The results obtained with the above-mentioned products were, however, not entirely satisfactory, so that a further improvement was desirable.
In U.S. Pat. No. 4,526,972, U.V. Stabilizers are described containing polyoxyalkylene derivatives of tetramethyl piperadines ##STR7## In this work R is H or CH.sub.3.
The invention of U.S. Pat. No. 4,578,454 relates to novel products of a polymeric nature, which contain piperidine radicals and have shown a surprising and unforeseeably higher activity as light stabilizers for synthetic polymers, as compared with products of the state of the art. The activity of the novel stabilizers is of particular interest for polyolefin films, fibres and tapes.
That invention relates particularly to polyaminoamides of the general formula (I): ##STR8## in which R.sub.1 is hydrogen, O., CH.sub.2 CN, C.sub.1 -C.sub.12 -alkyl, C.sub.3 -C.sub.12 -alkenyl or -alkynyl, substituted or unsubstituted C.sub.7 -C.sub.12 -aralkyl or C.sub.1 -C.sub.12 -acyl, R.sub.2 is C.sub.2 -C.sub.18 -alkylene, C.sub.5 -C.sub.18 -cycloalkylene, C.sub.6 -C.sub.18 -arylene or C.sub.7 -C.sub.18 -aralkylene, R.sub.3 is hydrogen, C.sub.1 -C.sub.18 -alkyl, C.sub.5 -C.sub.18 -cycloalkyl, substituted or unsubstituted C.sub.6 -C.sub.18 -aryl, substituted or unsubstituted C.sub.7 -C.sub.18 -aralkyl or a radical of the formula (II). ##STR9## in which R.sub.1 is as defined above, the R.sub.4 's are ##STR10## radicals with the carbonyl group attached either to X or to N and in which m is an integer from 1 to 12, X is a divalent radical containing 1 or more hetercyclic radicals of the formula (III), (IV) or (V). ##STR11## in which R.sub.1, R.sub.2 and R.sub.3 are as defined above, p is zero or 1, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, R.sub.12, R.sub.13 and R.sub.14 are hydrogen or methyl, R.sub.15 is hydrogen. C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.18 cycloalkyl, substituted or unsubstituted C.sub.6 -C.sub.18 aryl, substituted or unsubstituted C.sub.7 -C.sub.18 aralakyl or a radical of the formula (II), and n is an integer from 2 to 100.
A good review of this subject is found in "Polymer Stabilization and Degradation", P. P. Klemchuk, Editor, American Chemical Society, Washington, D.C. 1985, Chapters 1-4, 11.
In the instant invention there has been devised a method for preparing a piperidine derivative having a structure containing a polyalkoxylamide, urea or urethane backbone. This novel structure allows certain advantages over the art. The advantages include.
1. Simple preparation methods. PA1 2. Low cost products from readily available starting materials. PA1 3. Products which can be either water-soluble or water-insoluble. PA1 4. Products with a low volatility which are difficult to remove from the polymers they are protecting. PA1 1. Simple preparation methods. PA1 2. Colorless to lightly colored products. PA1 3. Water-soluble and water-insoluble products. PA1 4. Low cost raw materials. PA1 5. Liquid or low melting solids products for case of handling.